Minamata disease in Brazil and Indonesia

An unsolicited email today speaks of investment opportunities in diamond mining in the region known as the SÃ£o Luis River Basin, in Brazil. The words "Brazil" and "mining" never sit well together for any environmentalist, so I set off on a mini exploration with trusted guide Cynthia Google, and soon found a few additional words that don't sit well with environment.

Mercury, for example, the heavy metal that causes "Minamata disease". The SÃ£o Luis River Basin reference found on Google reports the region as having the "highest mercury levels in human hair samples".

Mercury discharged into Minamata Bay from Shin Nippon Chisso Hiryo, a company manufacturing acetaldehyde, found its way into the food chain and inevitably into the diet of the local fishing community, manifesting as gross birth defects and neurological disturbance.

An article by M.C.N. Pinheiro et al. in the Brazilian Journal of Medical and Biological Research entitled 'Comparative study of human exposure to mercury in riverside communities in the Amazon region' concludes: "...mercury levels detected in exposed populations of the TapajÃ³s River basin may be dangerous not only because they are above the World Health Organization limits, but also because the simultaneous mercury detection in non-exposed populations with similar characteristics provided a valid control and revealed lower mercury levels".

According to the article, "Approximately 2,000 to 3,000 tons of mercury have already been released into the Amazon environment" as part of the process of recovering gold. "Brazil is the first country in South America and the second in the world in gold production (80% from informal mining or 'garimpagem')."

Closer to home (Australia), mercury has also been used by illegal miners in Indonesia, where, according to one article, 'Influence of illegal gold mining on mercury levels in fish of north Sulawesi's Minahasa Peninsula', it is estimated that more than 200 tonnes of mercury is used annually.

As with the Amazon, mercury is also finding its way into the food chain in the areas studied: "Fish from the region of the illegal mine contained 30 times the mercury content of fish at the reference site. Moreover, whole fish tissue levels were four times those recommended by the World Health Organization for consumption restrictions and often two-fold higher than recommended for total restriction on fish consumption. The environmental and human health implications of these levels are of grave concern; citizen education programmes are required to alert indigenous peoples of the risks associated with mercury exposure and fish consumption guidelines put into place."